From February 14 to February 20, Lenny’s is offering a coupon for a free half-pound sub to all existing and new Facebook fans. Brent Alvord, president of Lenny’s, says the brand had about 11,000 fans on Facebook on Sunday. At time of press, Lenny’s had just more than 34,000 fans.

Alvord says the promotion “offers a good incentive for somebody to come in and give us a try.”

“We are taking a calculated risk that the food cost investment of giving away the free sandwich and the labor investment of giving away the free sandwich is worth it in an effort to convert those people who are trying our product for the first time,” Alvord says.

Many quick serves have offered free products to new fans on Facebook in an effort to boost their social media presence. Just last week, Taco Bell announced it would give away up to 10 million free tacos on Facebook.

But a 150-unit chain giving away its signature product is a different story. Still, Alvord says the new promotion shouldn’t put the company in a hole.

“Most of the people who come in to get the free sandwiches are probably going to get chips and a drink,” he says. “The margin on chips and a drink help offset the food costs on the sandwich.”

Customers coming in with a coupon might also bring a friend with them, Alvord says, which helps to further offset any costs incurred during the promotion.

Alvord says Lenny’s plans to continue a heavy investment into Facebook and other social media networks, but says the company “isn’t all about freebies, and it isn’t all about discounts.”

Instead, he says, Lenny’s is ramping up its customer engagement efforts through social media, using it to build a buzz about the brand—one that doesn’t have the traditional, measurable return on investment.

“The reality is you can’t sell on Facebook; you can’t do your typical marketing tactics,” Alvord says. “You have to put a different hat on, and you have to think of it as a communication tool.”